Catheter with attached flexible side sheath

ABSTRACT

A method of positioning a main stent at a vessel bifurcation includes positioning a main guidewire in the main vessel; and advancing a stent delivery system to a position proximate the bifurcation. The stent delivery system includes a catheter with a flexible side sheath attached thereto and a main stent positioned over the catheter. The flexible side sheath is positioned to pass through the side opening in the main stent. The method also includes advancing a branch guidewire through the flexible side sheath and into the branch vessel; and subsequently, advancing the catheter over the main guidewire while advancing the flexible side sheath over the branch guidewire while viewing relative movement of a marker positioned on the flexible side sheath with respect to at least one marker positioned on the catheter.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.10/762,562, filed on Jan. 23, 2004, now U.S. Pat. No. 8,211,167, issuedJul. 3, 2012, which is a divisional application of U.S. application Ser.No. 09/455,299, filed on Dec. 6, 1999, now U.S. Pat. No. 6,692,483,issued Feb. 17, 2004, the entire disclosures of which are both herebyincorporated herein by reference.

TECHNICAL FIELD

The present invention relates to catheter systems for delivering stents.

BACKGROUND OF THE INVENTION

A type of endoprosthesis device, commonly referred to as a stent, may beplaced or implanted within a vein, artery or other tubular body organfor treating occlusions, stenoses, or aneurysms of a vessel byreinforcing the wall of the vessel or by expanding the vessel. Stentshave been used to treat dissections in blood vessel walls caused byballoon angioplasty of the coronary arteries as well as peripheralarteries and to improve angioplasty results by preventing elastic recoiland remodeling of the vessel wall. Two randomized multicenter trialshave recently shown a lower restenosis rate in stent treated coronaryarteries compared with balloon angioplasty alone (Serruys, P W et al.,New England Journal of Medicine, 331: 489-495 (1994) and Fischman, D Let al., New England Journal of Medicine, 331:496-501 (1994)). Stentshave been successfully implanted in the urinary tract, the bile duct,the esophagus and the tracheo-bronchial tree to reinforce those bodyorgans, as well as implanted into the neurovascular, peripheralvascular, coronary, cardiac, and renal systems, among others. The term“stent” as used in this Application is a device which is intraluminallyimplanted within bodily vessels to reinforce collapsing, dissected,partially occluded, weakened, diseased or abnormally dilated or smallsegments of a vessel wall.

One of the drawbacks of conventional stents is that they are generallyproduced in a straight tubular configuration. The use of such stents totreat diseased vessels at or near a bifurcation (branch point) of avessel may create a risk of compromising the degree of patency of themain vessel and/or its branches, or the bifurcation point and alsolimits the ability to insert a branch stent into the side branch if theresult of treatment of the main, or main, vessel is suboptimal.Suboptimal results may occur as a result of several mechanisms, such asdisplacing diseased tissue, plaque shifting, vessel spasm, dissectionwith or without intimal flaps, thrombosis, and embolism.

As described in related copending U.S. patent application Ser. No.08/744,022 filed Nov. 4, 1996, now abandoned, Ser. No. 09/007,265 filedJan. 14, 1998, Ser. No. 08/935,383 filed Sep. 23, 1997, U.S. ProvisionalApplication No. 60/088,301 filed Jun. 5, 1998, and PCT PatentApplication Publication No. WO 99/00835 filed Jan. 14, 1998, systemshave been developed for deploying a main stent in a main vessel at theintersection of a main vessel and a branch vessel with a branch stentextending into a branch vessel through a side opening in the main stent.Unfortunately, several difficulties exist when attempting to positionsuch an arrangement of a main and branch stents at a vesselintersection.

For example, the insertion of separate guidewires into both the mainvessel and the secondary vessel is required before positioning a mainstent in a main vessel with a branch stent projecting through a sideopening in the main stent into a branch vessel. Main and branch stentsare then advanced over the separate guidewires which have beenpre-guided one after another into the respective main and branchvessels, such that the main stent can be deployed within the main vesseland the branch stent can be deployed through the side opening in themain stent into the branch vessel. Unfortunately, when attempting toguide two such separate guidewires through the main vessel such that oneenters the branch vessel, the two guidewires typically tend to wraparound one another and become entangled. Additionally, time and effortis required to individually position each of the two guidewires oneafter another.

An additional disadvantage of conventional stents is the difficulty invisualizing the stents during and after deployment, and in general, thefact that they are not readily imaged by low-cost and easy methods, suchas x-ray or ultrasound imaging.

SUMMARY OF THE INVENTION

The present invention provides a stent delivery system which comprises acatheter with a flexible side sheath attached thereto. In a preferredaspect of the invention, the catheter is adapted to receive a firstguidewire therethrough, and the flexible side sheath is adapted toreceive a second guidewire therethrough.

As will be explained, an advantage of the present stent delivery systemis that it may be used for deploying a main stent in a main vessel witha side opening in the main stent being aligned with the ostium of abranch vessel. In additional preferred aspects, a branch stent can alsobe deployed in the branch vessel with the branch stent passing throughthe side opening in the main stent.

Accordingly, the present invention also sets forth methods ofpositioning a main stent at a vessel bifurcation such that a sideopening in the main stent is positioned at the ostium of a branchvessel. In preferred aspects, a main guidewire is first positioned inthe main vessel such that a distal end of the main guidewire extendspast the bifurcation. Thereafter, the stent delivery system, (comprisinga catheter with an attached flexible side sheath), is advanced to aposition proximate the bifurcation, wherein the catheter is advancedover the main guidewire, and wherein the main stent is positioned overthe catheter. In preferred aspects, the flexible side sheath ispositioned to pass through the interior of the main stent, (positionedover the distal end of the catheter), and out of the side opening in themain stent.

Thereafter, a branch guidewire is advanced through the flexible sidesheath and into the branch vessel. To assist in guiding the secondguidewire into the branch vessel, the flexible side sheath maypreferably taper to a narrow distal end, which may be curved slightlyoutwardly.

Subsequently, the stent delivery system is advanced with the catheteradvancing over the main guidewire while the flexible side sheathconcurrently advances over the branch guidewire. In one aspect of theinvention, the side opening in the main stent is positioned in alignmentwith the ostium of the branch vessel due solely to the presence of thebranch guidewire extending from an interior of the main stent outthrough the side opening in the main stent and into the branch vessel.

In another more preferred aspect of the invention, however, the sideopening in the main stent is positioned in alignment with the ostium ofthe branch vessel by viewing relative movement of radiopaque markerspositioned on each of the catheter and the flexible side sheath. In thisaspect of the invention, the relative marker movement indicates that aportion of the flexible side sheath which is positioned adjacent theside opening in the main stent is advancing into the ostium of thebranch vessel, thereby indicating the position of the side opening ofthe main stent with respect to the ostium of the branch vessel. In thisaspect of the invention, the flexible side sheath will deflect into thebranch vessel as it is advanced over the second guidewire, (while thecatheter itself moves distally along through the main vessel over thefirst guidewire).

Such relative movement of the radiopaque markers may be viewed as arotation of a marker on the flexible side sheath with respect to amarker(s) on the catheter, or as a separation between the marker on theflexible side sheath with respect to a marker(s) on the catheter. Incertain aspects, the marker on the flexible side sheath is positionedadjacent a marker on the catheter, such that the relative marker motionwill be viewable in an image as a separation occurring between the twomarkers. In a preferred aspect of the invention, the relative movementof the markers on the catheter and flexible side sheath can be observedfluoroscopically as the markers are radiopaque and are preferably madeof suitable materials including tungsten and gold.

In addition, a plurality of markers may be positioned on the catheterwith a marker positioned at locations corresponding to each of theproximal and distal ends of the main stent. A medial marker may also beincluded, positioned halfway between the distal and proximal markers,for indicating the position of the side hole in the main stent, (whichis preferably positioned halfway between the distal and proximal ends ofthe stent).

In additional aspects of the present invention, the main stent isdeployed in the main vessel, (such as by an inflatable balloon at thedistal end of the catheter). Thereafter, a branch stent may be advancedthrough the at least partially deployed main stent and positioned in thebranch vessel. Preferably, the branch stent is advanced through the atleast partially deployed main stent by a second catheter, which thendeploys the branch stent in the branch vessel, (such as by an inflatableballoon at the distal end of the second catheter).

To deploy the branch stent, the delivery system, (comprising thecatheter and attached flexible side sheath), may be removed leaving thetwo guidewires in place such that the second catheter can then beadvanced over the second guidewire and into the branch vessel. As such,the second catheter can then be advanced over the second guide wire withits distal end extending into the branch vessel.

An advantage of the present stent delivery system is that it avoidshaving to separately position first and second guidewires within therespective main and branch vessels prior to deployment of the main andbranch stents thereover. Rather, with the present invention, only asingle guidewire needs to initially be placed within the main vessel,with the delivery system subsequently deploying both the main and branchstents thereover.

The main stent may optionally include outwardly expandable portionswhich can be expanded from an initial position which is flush with thecylindrical body of the stent to protrude outwardly from the sideopening in the main stent, thereby anchoring into the walls of thebranch vessel, holding the side opening in registry with the ostium ofthe branch vessel. In an exemplary aspect, the cylindrical body of themain stent has an even surface, with an expandable portion positionedwithin the side opening of the cylindrical body, such that it is flushwith the cylindrical body prior to expansion.

In addition, the branch stent may optionally comprise a contactingportion at its proximal end to secure the proximal end of the branchstent to the side opening in the main stent. In an exemplary aspect, thecontacting portion comprises a flared proximal end.

Applications of the present system include the cardiac, coronary, renal,peripheral vascular, gastrointestinal, pulmonary, urinary andneurovascular systems and the brain. Further advantages of the presentstent delivery system are that it provides an improved stent deliveryapparatus, which may deliver main and branch stents to: 1) completelycover the bifurcation point of bifurcation vessels; 2) be used to treatlesions in one branch of a bifurcation while preserving access to theother branch for future treatment; 3) allow for differential sizing ofthe stents in a bifurcated stent apparatus even after a main stent isimplanted; 4) treat bifurcation lesions in a bifurcated vessel where thebranch vessel extends from the side of the main vessel; and 5) be markedwith, or at least partly constructed of, material which is imageable bycommonly used intraluminal catheterization visualization techniquesincluding but not limited to ultrasound or x-ray.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustration of the present stent delivery system showing acatheter with a flexible side sheath attached thereto.

FIG. 2 A is a close up illustration of the distal end of the stentdelivery system of FIG. 1 with a main stent positioned thereon.

FIG. 2B is a sectional side elevation view corresponding FIG. 2A.

FIG. 3 is an illustration of a placement of first guidewire within amain vessel.

FIG. 4 is an illustration of the catheter and attached flexible sidesheath of the present invention advanced over the first guidewire to aposition near the ostium of the branch vessel.

FIG. 5 is an illustration of the second guidewire being advanced out ofthe distal end of the side sheath, through a side opening in a mainstent and into the branch vessel.

FIG. 6A is an illustration of the catheter and attached flexible sidesheath advanced over the first and second guidewire such that the distalend of the flexible side sheath is deflected into the branch vessel,showing the separation between radiopaque markers on the catheter andflexible side sheath.

FIG. 6B is a sectional side elevation view corresponding FIG. 6A.

FIGS. 7A and 7B are an illustrations of a branch stent advanced over thesecond guidewire and through the side opening in the main stent and intothe branch vessel.

FIG. 8 is an illustration of the deployment of the branch stent by aballoon disposed on a second catheter received over the secondguidewire.

FIG. 9 is an illustration of the fully deployed main and branch stentswith the guidewires and stent delivery system removed.

FIG. 10 shows an embodiment of the present invention with outwardlyexpandable portions disposed around the side opening on the main stent.

DESCRIPTION OF THE SPECIFIC EMBODIMENTS

The present invention comprises methods of positioning a main stent at avessel bifurcation such that a side opening in the main stent ispositioned at the ostium of a branch vessel, and sets forth variousapparati and kits for performing the preferred methods.

In addition, the present invention comprises methods for positioning amain and a branch stent at a vessel bifurcation, wherein the branchstent is deployed through a side opening in the main stent, with theside opening in the main stent being positioned in registry with theostium of the branch vessel.

A novel stent delivery system is provided for accomplishing thepreferred methods. Referring to FIGS. 1 to 2B, the present stentdelivery system 10 comprises a first catheter 12 having an attachedflexible side sheath 14. An inflatable balloon 11 is preferablypositioned at the distal end of first catheter 12. As is shown in FIGS.5 to 6B, first catheter 12 is receivable over a first guidewire 21 andflexible side sheath 14 is receivable over a second guidewire 31. As canbe seen, stent 25 is preferably crimped down onto flexible side sheath14, as shown. Preferably, stent 25 is initially crimped onto balloon 11with distal end 16 of flexible side sheath 14 projecting outwardlythrough side opening 27 as shown.

The present invention provides a method of positioning a main stent 25at a vessel bifurcation B such that a side opening 27 in main stent 25is positioned at the ostium of a branch vessel Br, as follows.

Referring to FIG. 3, a main guidewire 21 is first positioned in the mainvessel M such that a distal end 22 of main guidewire 21 extends pastbifurcation B. Referring to FIG. 4, stent delivery system 10 is thenadvanced to a position proximate bifurcation B, wherein catheter 12 isreceived over first guidewire 21, and wherein main stent 25 ispositioned over catheter 12 with flexible side sheath 14 positioned topass through the interior of main stent 25 and out of side opening 27 inmain stent 25, as shown. Referring to FIG. 5, second guidewire 31 isthen advanced through flexible side sheath 14 attached to catheter 12and into branch vessel Br.

In one aspect of the invention, side opening 27 in main stent 25 ispositioned in alignment with the ostium of branch vessel Br simply bythe presence of second guidewire 31 extending from an interior of mainstent 25 out through side opening 27 in main stent 25 and into branchvessel Br. In this aspect of the invention, the insertion of a branchstent over guidewire 31 through side opening 27 in main stent 25 andinto branch vessel Br serves to align the side opening 27 with theostium of branch vessel Br.

In another more preferred aspect, however, stent delivery system 10,(comprising catheter 12 and attached flexible side sheath 14), aresubsequently advanced distally in direction D to the position as shownin FIGS. 6A and 6B, with catheter 12 being advanced over first guidewire21 while flexible side sheath 14 is advanced over second guidewire 31.In this aspect of the invention, an operator views relative movementbetween a radiopaque marker positioned on the flexible side sheath withrespect to at least one radiopaque marker positioned on the catheter,wherein the relative marker movement indicates that a portion of theflexible side sheath adjacent the side opening in the main stent isadvancing into the ostium of the branch vessel, thereby indicating theposition of the side opening of the main stent with respect to theostium of the branch vessel.

Specifically, referring to FIGS. 2B and 6B, a distal marker 50, aproximal marker 51 and a medial marker 52 may be disposed on catheter12. Preferably, the location of proximal marker 51 corresponds to thelocation of the proximal end of stent 25, the location of distal marker50 corresponds to the location of the distal end of stent 25, and thelocation of medial marker 52 corresponds to the location of side opening27 of stent 25. At least one marker 55 is positioned on flexible sidesheath 14 as shown. Preferably, marker 55 is positioned adjacent tomedial marker 52.

As can be seen by comparing FIGS. 2B to 6B, as stent delivery system 10is advanced distally such that the distal end of flexible side sheath 14is received in branch vessel Br, (FIG. 6B), marker 55 will move indirection R relative to markers 50, 51 and 52. In particular, anincreasing separation distance will occur between marker 55 positionedon flexible side sheath 14 and marker 52 positioned on catheter 12 ascatheter 12 is advanced distally over first guidewire 21 while flexibleside sheath 14 is simultaneously advanced distally over second guidewire31.

In an additional aspect of the invention, each of markers 52 and 55 areslightly elongated and rectangle shaped (as shown), such that relativerotational movement therebetween can also be observed. Marker 55 may bemade of tungsten and markers 50, 51 and 52 may be made of gold.

When the operator views the relative motion between markers 52 and 55,this indicates that the portion of flexible side sheath 14 positionedadjacent side opening 27 is disposed at the ostium of branch vessel Br.By viewing the position of markers 50, 51 and 52, the operator can alsodetermine the position of the distal and proximal ends of stent 25 andthe position of side opening 27 with respect to the ostium of branchvessel Br.

The present invention also comprises systems for deploying a branchstent into branch vessel Br with main stent 25 positioned such that sideopening 27 is in registry with the ostium of branch vessel Br. In theseaspects of the invention, as illustrated in FIGS. 7 through 10, branchstent 40 is advanced through the interior of main stent 25, passingthrough side opening 27 and into branch vessel Br.

FIG. 7A is an illustration of branch stent 40, (disposed on the distalend of a second catheter 26), being advanced over second guidewire 31,passing through side opening 27 in main stent 25 into branch vessel Br.As can be seen, in one aspect of the present invention, stent deliverysystem 10 may first fully deploy main stent 25 and then be removed.Thereafter, second catheter 26 can be advanced over second guidewire 31to position stent 40 for deployment in the branch vessel.

In an alternative aspect of the invention, as shown in FIG. 7B, stent 25may be partially deployed in main vessel M, and second catheter 26 maythen be advanced through the partially expanded interior of main stent25, passing out through side opening 27 in main stent 25 while stentdelivery system 10 remains adjacent bifurcation B.

FIG. 8 is an illustration of the deployment of branch stent 40 by aballoon 13 disposed on the distal end of second catheter 26, which isitself received over second guidewire 31. In this aspect of theinvention, an inflatable balloon 13 disposed at the distal end of secondcatheter 26 is used to deploy branch stent 40.

FIG. 9 is an illustration of the fully deployed main and branch stents25 and 40 with the guidewires (21 and 31) and stent delivery system (10)removed. As can also be seen, stent 40 may further comprise a contactportion 42 which remains disposed within side opening 27, therebysecuring the proximal end of stent 40 to side opening 27 of stent 25,thereby providing a bifurcated stent arrangement covering vesselbifurcation B. Such a contacting portion 42 is further described incopending PCT Patent Application Publication No. WO 99/00835, filed Jan.14, 1998.

Lastly, FIG. 10 shows an embodiment of the present invention withoutwardly expandable portions disposed around the side opening on themain stent. Specifically, balloon 13 on catheter 26 can also be inflatedto deploy radially expandable portions 29 which extend laterally outwardfrom an initial position flush with the cylindrical body of stent 25 toa position where portions 29 (disposed around the edges of side opening27), are anchored against the walls of branch vessel B, such that sideopening 27 is positioned in registry with the ostium of branch vessel B.Further description of such radially expandable portions 29 which extendlaterally outward from the edges of side opening 27 is set forth inPublished PCT Patent Application No. WO 99/00835 filed Jan. 14, 1998,incorporated herein by reference in its entirety.

The present invention also comprises kits including the apparatus of thepresent invention with instructions for use setting forth any of theherein disclosed methods for use.

What is claimed is:
 1. A method of positioning first and second stentsat a vessel bifurcation such that a portion of each stent is disposed ina main vessel portion proximal of the bifurcation and a portion of eachstent is disposed in a branch vessel or main vessel portion distal ofthe bifurcation, the method comprising: first, advancing a firstcatheter including a first inflatable balloon having a first expandablestent thereon through the main vessel portion proximal of thebifurcation to the bifurcation such that a distal end of the firstcatheter extends past the vessel bifurcation and into the main vesselportion distal of the bifurcation, wherein the first catheter isadvanced such that a distal portion of the first stent is positioned inthe main vessel portion distal of the bifurcation and a proximal portionof the first stent is positioned in the main vessel portion proximal ofthe bifurcation; second, only partially expanding the first stent in themain vessel portion proximal of the bifurcation and the main vesselportion distal of the bifurcation; third, after partially expanding thefirst stent, advancing a second catheter including a second inflatableballoon having a second expandable stent thereon through the main vesselportion proximal of the bifurcation to the bifurcation and through thepartially expanded first stent such that a distal end of the secondcatheter extends through a side opening in the partially expanded firststent, past the vessel bifurcation and into the branch vessel, whereinthe second catheter is advanced such that a distal portion of the secondstent is positioned in the branch vessel and a proximal portion of thesecond stent is positioned in the main vessel portion proximal of thebifurcation; and fourth, after advancing the second stent through thepartially expanded first stent, then fully expanding the first stent andexpanding the second stent in the main vessel portion proximal of thebifurcation and the branch vessel; wherein a proximal portion of each ofthe first and second stents resides in the main vessel portion proximalof the bifurcation, a distal portion of the first stent resides in themain vessel portion distal of the bifurcation, and a distal portion ofthe second stent resides in the branch vessel.
 2. The method of claim 1,further comprising, prior to the first step of advancing a firstcatheter, the step of inserting a first guidewire through the mainvessel portion proximal of the bifurcation and into the main vesselportion distal of the bifurcation and inserting a second guidewirethrough the main vessel portion proximal of the bifurcation and into thebranch vessel.
 3. The method of claim 2, wherein the first catheter isadvanced over the first guidewire and the second catheter is advancedover the second guidewire.
 4. The method of claim 1, wherein at leastpart of the proximal portion of the first stent overlaps at least partof the proximal portion of the second stent.